1. Technical Field
The present disclosure relates to projection zoom lenses.
2. Description of Related Art
In a typical projector, a projection lens must have a sufficient back focal length to allow a prism to be disposed between the projection lens and a digital micro-mirror device. Therefore, a reverse telephoto lens is utilized as the basic is optical framework of the projection lens because of its long back focal length.
However, since the front lens group and the rear lens group of a reverse telephoto lens are asymmetrical relative to an aperture stop, coma, lateral color and distortion problems occur easily. Therefore, many in the industry are striving to provide an image quality with a high resolution and low distortion under conditions where there is a sufficient back focal length.